Age-related changes to behavior or cognitive functioning are typically interpreted within a developmental framework. Researchers hypothesize that age-related improvements in neural function (i.e., increased neural connectivity or functional specialization) are responsible for improvements in ADHD hyperactive/impulsive symptomatology. A body of evidence indirectly supports such contentions. Adults and adolescents are developmentally distinct with regard to brain structure and function. Structural MR studies consistently show increases in white matter volume throughout early childhood to early adulthood (Caviness et al.,1996; Giedd et al., 1999) reflecting increasing connectivity among cortical areas, especially in reciprocal connections between prefrontal and posterior brain areas (Goldman-Rakic, 1987). Gray matter is seen to increase in a linear fashion until puberty and decrease during adolescence in most brain regions. These curves peak in the frontal and parietal lobes at about age 12, the temporal lobes at age 16, and the occipital lobes at increase until 20 (Giedd et al., 1999). These findings are paralleled by histological animal and in vivo studies of human brain development that show a sharp reduction in syntapogenesis at puberty, followed by an period of synaptic pruning that continues at a similar rate throughout middle adulthood (Bourgeois, 2001). These changes presumably reflect the shaping of brain structure/function following experience (Purves, 1988), and such changes likely reflect continuing performance improvements on some cognitive tests throughout adolescence.